Cities support more native biodiversity than previously thought

Seagulls are part of the urban biota in Montreal (photo courtesy Chris Lepczyk).

The rapid conversion of natural lands to cement-dominated urban centers is causing great losses in biodiversity. But Chris Lepczyk, an associate professor in the College of Tropical Agriculture and Human Resources at the University of Hawaiʻi at Mānoa, is a contributor to a new study showing that surprisingly high numbers of plant and animal species persist and even flourish in urban environments. In fact, hundreds of bird species and thousands of plant species can be found in a single city.

Contrary to conventional wisdom that cities are a wasteland for biodiversity, the study, involving 147 cities worldwide, found that while a few species — such as pigeons and annual meadow grass — are shared across cities, overall the mix of species in cities reflects the unique biotic heritage of their geographic location.

“Cities and urban areas are not as devoid of biodiversity as we may think,” said coauthor Lepczyk, who is in the Department of Natural Resources and Environmental Management at UH Mānoa. “Our findings indicate that cities provide habitat for a number of plants and animals. This is important because the majority of people in the U.S. and around the world live in urban areas, and so biodiversity in cities is critical for people to have a direct connection to nature.”

Unlike previous urban biodiversity research, this study looks beyond the local impacts of urbanization and considers overall impacts on global biodiversity. The research team created the largest global dataset to date of two diverse taxa in cities: birds (54 cities) and plants (110 cities).

Conserving green spaces, restoring native plant species and adding biodiversity-friendly habitats within urban landscapes could support more bird and plant species. “It is true that cities have already lost a substantial proportion of their region’s biodiversity,” said Madhusudan Katti, a faculty member in the Department of Biology at California State University, Fresno. “This can be a cup half-full or half-empty scenario. If we act now and rethink the design of our urban landscapes, cities can play a major role in conserving the remaining native plant and animal species and help bring back more of them.”